DESCRIPTION (Applicant's Abstract): There is demonstrated clinical need for a universal internal fixation system that addresses problems currently encountered in the fixation of tubular bone fractures. We propose to develop a resorbable, injectable internal fixation material especially for the treatment of tubular fractures of the hand. The proposed material is a new version of our resorbable cement: an injectable, biodegradable cement which expands to a rigid, dense foam prior to setting. The premise is that expansion of the foam against the adjacent tissue when it is injected into the cavity evenly distributes the material within the intramedullary canal prior to cure. Setting of the cement is based on crosslinking of the resorbable polymer (polypropylene fumarate, PPF) with foaming induced by generation of carbon dioxide via inclusion of citric acid (CA) and sodium bicarbonate (SB). Phase I will investigate the feasibility of this cement to support repair of tubular hand fractures. In vitro measurements of the physicochemical and mechanical properties of the cement will provide a basis for developing a correlative temporal history of device degradation and strength. In vivo studies will then assess the feasibility of this space-filling cement to support fracture fixation in an intramedullary rat model using histomorphometric techniques. The overall aim of Phase I is thus to determine the reasonability of the proposed design to support the healing process from both structural and compositional perspectives. PROPOSED COMMERCIAL APPLICATION: Clinical reports clearly indicate there is a need for an improved fixation system, especially for fractures of the tubular bone of the hand. Further, the care of such fractures is a special challenge to physicians using rigid fracture fixation devices. Our concept of an injectable, space-filling cement addresses restoration of both the bones and the surrounding soft-tissue envelope with the goal of early restoration of joint movement and complete rehabilitation.